using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Azimuth.Polynomials;

namespace Azimuth.UnitTests.Polynomials
{
	public class VectorQuadratic : UnitTestSharp.TestFixture
	{
		/// <summary>
		/// Simulates a ballistic vector shooting mostly up with wind to the right
		/// intersecting a growing circle at time t = 1, 2, and a tangent hit at t = 17
		/// </summary>
		public void Expansive()
		{
			Vector accel = new Vector(1, -10);
			Vector vel = new Vector(0, 100);
			Vector position = new Vector(-30.5, -135);

			Scalar r1 = 50;
			Scalar r2Sq = 2837.25;
			Scalar r2 = Math.Sqrt(r2Sq);
			Scalar r17Sq = 114 * 114 + 120 * 120;
			Scalar r17 = Math.Sqrt(r17Sq);

			Scalar r0 = -17.0 / 15.0 * r2 + 1.0 / 120.0 * r17 + 17.0 / 8.0 * r1;
			Scalar rV = 6.0 / 5.0 * r2 - 1.0 / 80.0 * r17 - 19.0 / 16.0 * r1;
			Scalar rA = -2.0 / 15.0 * r2 + 1.0 / 120.0 * r17 + 1.0 / 8.0 * r1;

			//Just some sanity check to tell us we did the magic numbers right:
			CheckEqual(r1, r0 + rV + 0.5 * rA);
			CheckEqual(r2, r0 + rV * 2 + 2 * rA);
			CheckEqual(r17, r0 + rV * 17 + 17 * 17 / 2.0 * rA);

			CheckEqual(r1 * r1, (position + vel + accel / 2.0).LengthSquared());
			CheckEqual(r2Sq, (position + 2 * vel + 2 * accel).LengthSquared());
			Scalar rad17 = r0 + 17 * rV + 17 * 17 / 2.0 * rA;
			Vector pos = position + 17 * vel + 17 * 17 / 2.0 * accel;
			CheckEqual(rad17 * rad17, pos.LengthSquared());

			// Ensure that we start outside the circle
			Check(position.LengthSquared() > r0 * r0);

			RootList list = Azimuth.Polynomials.VectorQuadratic.Solve(accel / 2, vel, position, rA / 2, rV, r0);
			CheckEqual(4, list.Roots.Count);
			CheckEqual(new RootList(new Scalar?[] { 1, 2, 17, 19.765065548 }), list);
		}
	}
}